Beyoncé may not have turned heads on the red carpet at Sunday night’s Grammy Awards, but that’s only because she didn’t actually walk down it. However, all eyes were glued to the star the second she took her seat inside the show in a stunning white dress. The designer behind the most talked about look of the evening? 31-year-old L.A.-based designer and Project Runway alum Michael Costello. How did Queen B end up wearing his floating design at music’s biggest night? From a party with Diddy that started it all, to a secret dress stash hidden in Costello’s design studio where the dress came from, he gave us all the scoop on that magnificent gown.

How did your gown end up on Beyoncé in the first place?
About two weeks ago, I was at a Golden Globes after-party hosted by Diddy and Beyoncé’s stylist, Ty Hunter was there, and he told me he wanted to “come and see me” for Grammys. As soon as we knew what day he was coming, we went out and bought a new chandelier, we bought new mannequins, we started making new pieces for her right then and there! When he came in, he saw a few options that he liked, but he said he wanted to do something ‘naked.’ So that’s when we hit up the secret stash.

Wait, a secret stash? Tell us more!
Yes, it’s a collection of dresses that we keep hidden upstairs, and we never show it to anyone, but we brought it down and [Hunter] was like, ‘yes!’ He loved it. The dress wasn’t even ready yet. The zipper wasn’t installed, the neckline wasn’t finished, but he saw something in it, and he knew she was going to love it. The dress is a part of the “Winter Wonderland” collection I’m showing at New York Fashion Week-- everything [in the collection] is pretty much naked and transparent with lacy fabrics; it’s a take from winter and all white, with little pops of color.

Give us the scoop on how the dress was created.
It's constructed of three different fabrics: White lace overlay, nude mesh underlay, and a fish-netting behind the nude mesh to give the dress a little bit of stretch and support. The dress is entirely hand sewn and sewn to this nude illusion fabric. It’s almost paper thin and you can’t even tell it’s fabric -- it looks like the lace is just floating on the body. The sleeves have delicate flowers that cascade down one arm and into the other arm, and the back has this really beautiful square cut out. It’s an A-symmetrical mermaid silhouette on the bottom.

That is quite intricate. How long did it take to make?
It’s trimmed in this really beautiful wire nylon hem called horse hair (a nylon fiber), and that’s the thing that took the longest on the dress to do. It took 14 hours just to get just the hemline into the dress! In fact, it took longer to get the hemline into the dress than to actually make the dress. The whole process took about three days.

What was your reaction when you first saw the dress on Beyoncé at the show?
I starting bawling! It's one thing when you dress somebody who’s an A-list celebrity, but it’s a completely different thing when you’re such a huge fan. She wore my dress when she could have worn anybody else’s dress in the world. That moment, I’m still living it.

You’re showing at New York Fashion Week on Feb. 8. What can we expect to see from the collection?
It’s a "Winter Wonderland" theme; it’s everything I’ve ever wanted to create, but drenched in whites and beautiful metallics. I wanted to celebrate the woman’s body and give her beautiful options, nothing too avant garde or overworked. I love effortless, easy style. I really wanted to do mermaid silhouettes, I had a little more inspiration from the movie American Hustle. I think you’re going to see things in the collection that celebrate women’s curves, that every women can wear no matter what her size is.

You also dressed Skylar Grey at the Grammys, in that fabulous nude gown. Tell us about that creation.That dress is brand new, she’s the first person to have it longer than it’s been in the showroom. It got made two days before the Grammys. We were just about to shoot the look book for it, [her team] saw the dress, they had to have it and so I gave it to them! My business partner and I collaborated on that dress together. There’s more youth there; stretch leather, perforated leather with a huge triangular cutout in the center.

What kind of woman does your clothing speak to?
I think she’s a risk taker. I think she knows she’s hotter than anything in this works but tries to be modest about it!